Method of forming a catalytic converter from a radially deformed pre-form member

ABSTRACT

A method is provided for manufacturing a catalytic converter. A metallic tubular member is provided. A section of the metallic tubular member is deformed radially inward to form a neck portion. The neck portion has a diameter less than an initial diameter of the metallic tubular member. The tubular member is separated at substantially an axial midpoint of the neck portion for obtaining a first pre-form member having a first conical-shaped end. At least one catalytic element is inserted in the first pre-form member. An outer surface of the first pre-form member is deformed radially inward for securing the catalytic element within the first pre-form member. The first pre-form member is spin-formed for forming a second conical-shaped end opposite the first conical-shaped end.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

REFERENCE TO A SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates in general to catalytic converters and in particular to a method of forming a catalytic converter.

2. Description of the Related Art

Catalytic converters include a catalytic element housed in a metallic housing. The housing includes a conical-shaped first end and a conical-shaped second end. The catalytic converters are typically manufactured by cutting a metallic tubular member to a desired length. The catalytic element is inserted within the housing and secured therein. The tubular member is loaded in a first spin forming machine to form the conical-shaped first end. After the spin forming operation is completed, the partially formed tubular member is unloaded from the first spin forming machine and loaded onto a second spin forming machine to form the second conical-shaped end. A disadvantage to spin forming is that it is a time consuming process since the part must be loaded and unloaded in separate machines and have spin forming operations performed on both ends. In addition, if an imperfection exists in the metallic tubular member prior to the spin-form operation, this operation will enlarge the existing imperfection, thereby producing a defective component which must be scrapped due to the fracture in the component.

BRIEF SUMMARY OF THE INVENTION

The present invention has the advantage of forming a catalytic converter assembly utilizing only one spin forming operation which provides cycle time reduction, cost savings, tooling wear, and scrap reduction. By utilizing only a single spin forming operation, time of manufacture is reduced. In addition, cost of tooling is reduced by the elimination of a spin forming machine. Furthermore, scrap is reduced as a result of the elimination of one of the two spin-forming operations which could otherwise enlarge existing fractures in the housing making the part unusable.

In one aspect of the present invention, a metallic tubular member is provided. A section of the metallic tubular member is deformed radially inward to form a neck portion by other than spin-forming. The neck portion has a diameter less than an initial diameter of the metallic tubular member. The tubular member is separated at substantially an axial midpoint of the neck portion for obtaining a first pre-form member having a first conical-shaped end. A catalytic element is inserted in the first pre-form member. An outer surface of the first pre-form member is radially deformed inward for securing the catalytic element within the first pre-form member. The first pre-form member is spin-formed for forming a second conical-shaped end opposite the first conical-shaped end.

Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross section view of catalytic converter assembly.

FIG. 2 is a perspective view of a tubular member used to form a housing of a catalytic converter assembly.

FIG. 3 is a side view of a plurality of neck portions formed by a forming tool.

FIG. 4 is a side view of a plurality of pre-form members.

FIG. 5 a is a section view of a pre-form member having a catalytic element assembled therein.

FIG. 5 b is a section view of a catalytic element secured within the pre-form member.

FIG. 6 is a cross section view of the end portion formed by the spin form operation.

FIG. 7 is a flowchart for a method for forming a catalytic converter assembly.

FIG. 8 is a flowchart for a method for forming a plurality of catalytic converter assemblies simultaneously.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, there is illustrated in FIG. 1, a cross section view of catalytic converter assembly 10. The catalytic converter assembly includes a housing 12 formed from a corrosion resistant alloy such as a stainless steel alloy.

At least one catalytic element 14 comprising a substrate and a support material is secured within an interior of the housing 12. An inner surface 16 of the housing 12 is pressed against the catalytic element 14 for securing the catalytic element 14 therein. Alternatively, the at least one catalytic element 14 may be stuffed into the housing 12.

The catalytic converter assembly 10 includes a first conical-shaped end 18 having a first port 20. The first port 20 is coupled to an exhaust pipe of a vehicle (not shown) extending from an internal combustion engine of the vehicle (not shown). The catalytic converter assembly 10 further includes a second conical-shaped end 22 having a second port 24. The second port 24 is coupled to the next portion of the exhaust system (not shown).

The first port 20 functions as an inlet port for receiving exhaust gases from the internal combustion engine such as hydrocarbons, carbon monoxide, and nitrogen oxides and converts the exhaust gases into carbon dioxide, water, nitrogen, and oxygen. The second port 24 functions as an exhaust port for discharging the converted gases to the discharging portion of the exhaust system (not shown).

FIG. 2 illustrates a tubular member 26 used to form the housing 12 of the catalytic converter assembly 10. The tubular member 26, as stated earlier, is a non-corrosive metallic housing having the inner surface 16 and an outer surface 30. The tubular member 26 is typically formed from a single strip of sheet metal. The sheet metal strip is wrapped length-wise and is welded along a seam for forming the tubular member 26. Alternatively, the tubular member 26 may be formed as a seamless tubular member by another process such as an extrusion process. The length of the tubular member 26 is preferably such that two or more housings may be produced from the tubular member 26.

FIG. 3 illustrates the forming neck portions in the tubular member 26 which are used to form a respective conical-shaped end for each respective housing section of the tubular member 26. A first forming tool, shown generally at 32, is brought into contact with the outer surface 30 of the tubular member 26. Preferably, the forming tool 32 is a swage tool or rotary swage tool. Alternatively, a roll forming or other forming operations may be used. As the tubular member 26 is rotated, the forming tool 32 is brought into contact with the outer surface 30 for deforming at least one section of the tubular member 26 radially inward thereby forming a neck portion 34 at each respective section. The neck portion 34 includes a pair of opposing conical-shaped sections 36 and 38 integrally connected by a substantially uniform cylindrical bridge section 40 such that a respective diameter at any given location of the neck portion 34 is smaller than an initial diameter of the tubular member 26. Multiple neck portions may be formed by the forming tool 32 at predetermined axial locations for creating two or more housings from a respective single tubular member.

FIG. 4 illustrates the tubular member 26 sectioned into a plurality of pre-form members. The tubular member 26 is separated by a transverse cut at substantially an axial midpoint 40 of each neck portion 34 for forming a first pre-form member 42 and a second pre-form member 44. In addition, if more than one neck portion 34 has been formed, then the tubular member 26 is also separated at substantially an axial midpoint 42 of each of the additional neck portions. Also, the tubular member is separated at substantially an axial midpoint between adjacent neck portions for forming four or more pre-form members. Separation of the tubular member at these respective locations may be performed by a cutting operation such as a laser cut, a saw cut, or a plasma cut. Other cutting operations may include a milling operation (e.g., high speed milling operation) for separating the respective pre-forms.

Each of the pre-forms include one conical-shaped end having a narrowed opening 46 and an opposing end 48 having a diameter substantially equal to the initial diameter of the tubular member 26.

FIGS. 5 a and 5 b illustrate the catalytic element 14 being assembled into the interior of the pre-form member 42. One or more catalytic elements 14 may be utilized within the pre-form member 42. The catalytic element 14 is inserted through the end 48. When the catalytic element 14 is axially positioned within the interior of the pre-form member 42, the outer surface 30 of the pre-form member 42 is deformed radially inward over a location that is axially aligned with the catalytic element 14. The outer surface 30 of the pre-formed member 42 is deformed radially inward forcing the interior surface 28 to press against the catalytic element 14 for securing the catalytic element 14 within the pre-form member 42.

FIG. 6 illustrates the formation of the second conical-shaped end 22 of the catalytic converter assembly 10. The first pre-form member 42 is mounted to a spin-forming machine, shown generally at 50. The open end 48 of the pre-form member 42 is deformed by the spin-form operation to form the second conical-shaped end 24. The second conical-shaped end 22 preferably is substantially the same shape as the first conical-shaped end 18.

The second pre-form member 44 and any additional pre-form members formed from the tubular member 26 are mounted to the spin forming machine 50 to form a respective second conical-shaped end of each additional pre-form member.

Radially deforming a first end of a respective housing section and spin forming a second end of the respective housing section reduces cost of tooling, time to manufacture, and scrap in comparison to spin-forming both ends of the respective housing section. Typically, a first dedicated machine is utilized to form the first conical-shaped end while a second dedicated machine is utilized to form the second conical-shaped end of the housing member. Elimination of the second spin forming operation eliminates the second dedicated machine which reduces tooling cost. Eliminating the second dedicated spin forming operation reduces time to manufacture which increases production output. Another advantage is the reduction of scrap and improved quality. Imperfections existing in the component end that is to be formed by spin forming will be enlarged by the spin form operation due to the rotation of the pre-form and spreading of the material during the spin-forming operation. Eliminating a spin form operation reduces the imperfections formed in the manufactured catalytic converter assembly enlarged by the spin forming operation. Lastly, since the neck portions are formed prior to cutting the tubular member, less material is required to be cut in the narrowed neck portion, and as a result, the tubular members may be cut faster and less (cutting) tooling wear is achieved.

FIG. 8 is a flowchart of a method for forming a catalytic converter assembly. In functional block 60, a tubular member is provided for forming a housing of a catalytic converter assembly. The tubular member may be a seamless single piece tube or may be a sheet metal strip that is wrapped and welded along a seam.

In functional block 61, a section of the tubular member is deformed radially inward to form a neck portion.

In functional block 62, the deformed tubular member is separated at substantially the midpoint of the neck portion for obtaining a first pre-form member and a second pre-form member. Each pre-form member includes a first end that is conical-shaped with a collar portion having a narrowed opening and a second end having an opening where the opening includes a diameter substantially equal to the initial diameter of the tubular member.

In functional block 63, a catalytic element is inserted within the first pre-form member.

In functional block 64, the outer surface of the first pre-form member is deformed radially inward for securing the catalytic element within the first pre-form member.

In functional block 65, the first pre-form member with the catalytic element secured therein is mounted in a spin-forming machine for forming a second conical-shaped end.

In functional block 66, the catalytic converter assembly is removed from the spin-forming machine. The same steps may be repeated for manufacturing a second catalytic converter formed from the second pre-form member that are obtained in functional block 62.

FIG. 9 illustrates a flowchart for a method for forming a plurality of catalytic converter assemblies. In functional block 70, a tubular member is provided for forming a plurality of catalytic converter assemblies. The tubular member has predetermined overall length which allows for the manufacture of multiple housings to be used to manufacture and assemble the plurality of catalytic converter assemblies.

In functional block 71, a plurality of neck portions are formed by deforming sections of the tubular member axially spaced from one another. The spacing between each of the neck portions are a predetermined length so that a sufficient amount of material is provided between the neck portions to allow each pre-form produced to be substantially the same size and length. This eliminates additional operations of having to remove additional material from the ends of the catalytic converter for forming same size housings.

In functional block 72, a plurality of tubular sections is obtained by cutting at substantially the midpoint of each neck portion. Each of the plurality of pre-form members includes a first end that is conical-shaped having a collar portion with a narrowed opening.

In functional block 73, the plurality of pre-form members is obtained by cutting at substantially the midpoint between each neck portion. Each of the pre-form members includes a second end having an opening where the diameter of the opening is substantially equal to the initial diameter of the tubular member.

Alternatively, step 73, may be performed before step 72.

In functional block 74, a catalytic element is inserted within a respective pre-form member.

In functional block 75, the outer surface of the respective pre-form member is radially deformed inward for securing the catalytic element within the respective pre-form member.

In functional block 76, the respective pre-form member having the catalytic element secured therein is mounted in a spin-forming machine and a second conical-shaped end is formed opposite the first conical-shaped end.

In functional block 77, the catalytic converter assembly is removed from the spin-forming machine.

In decision block 78, a determination is made whether any pre-form members formed earlier are available for manufacture and assembly into catalytic converter assemblies. If the determination made in decision block 74 is that an additional pre-form member requires manufacturing and assembly for forming a catalytic converter assembly, then a return is made to step 74 to assemble and manufacture a next catalytic converter assembly. If the decision in step 78 is made that no additional pre-forms are available, then a return is made to step 70 to form additional pre-form members.

In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope. 

1. A method of manufacturing a catalytic converter comprising the steps of: providing a metallic tubular member; deforming a section of said metallic tubular member radially inward to form a neck portion, said neck portion having a diameter less than an initial diameter of said metallic tubular member; separating said tubular member at substantially an axial midpoint of said neck portion for obtaining a first pre-form member having a first conical-shaped end; inserting a catalytic element in said first pre-form member; deforming radially inward an outer surface of said first pre-form member for securing said catalytic element within said first pre-form member; and spin-forming said first pre-form member for forming a second conical-shaped end opposite said first conical-shaped end.
 2. The method of claim 1 further comprising the steps of: providing a second pre-form member having a first conical-shaped end formed from said separation of said tubular member at said midpoint of said neck portion; inserting a respective catalytic element in said second pre-form member; deforming radially inward an outer surface of said second pre-form member that is radially aligned with said respective catalytic element for securing said respective catalytic element within said second pre-form member; and spin-forming said second pre-form member for forming a second conical-shaped end at an opposing end from said first conical-shaped end of said second pre-form member.
 3. The method of claim 2 wherein said step of deforming a section of said metallic tubular member is performed by a swage operation.
 4. The method of claim 2 wherein said swage operation includes a rotary swage operation.
 5. The method of claim 2 wherein said step of deforming a section of said metallic tubular member is performed by a roll forming operation.
 6. The method of claim 1 wherein said step of separating said tubular member at an axial midpoint is pre-formed by a laser cut operation.
 7. The method of claim 1 wherein said step of separating said tubular member at an axial midpoint is pre-formed by a milling operation.
 8. The method of claim 1 wherein said step of separating said tubular member at an axial midpoint is pre-formed by a cutting operation.
 9. The method of claim 1 wherein metallic tubular is formed from wrapped sheep metal strip having a welded seam.
 10. A method of manufacturing a plurality of catalytic converters from a metallic tubular member, said method comprising the steps of: (a) forming a plurality of axially spaced neck portions by deforming a section of said metallic tubular member, said plurality of axially spaced neck portions each having a diameter less than an initial diameter of said metallic tubular member; (b) cutting substantially a midpoint of said neck portions; (c) cutting substantially a midpoint between said neck portions; (d) inserting at least one respective catalytic element in a respective pre-form member; (e) deforming radially inward an outer surface of said respective pre-form member for securing said respective catalytic element within said respective pre-form member; and (f) spin-forming said respective pre-form member for forming a second conical-shaped end opposite said first conical-shaped end. repeating steps (d)-(f) for each respective pre-form member formed from said metallic tubular member.
 11. The method of claim 10 wherein said step of forming said neck portions is performed by a swage operation.
 12. The method of claim 11 wherein said swage operation includes a rotary swage operation.
 13. The method of claim 12 wherein said step of forming said neck portions is performed by a roll forming operation.
 14. The method of claim 10 wherein said step of separating said tubular member at an axial midpoint is pre-formed by a laser cut operation.
 15. The method of claim 10 wherein said step of separating said tubular member at an axial midpoint is pre-formed by a milling operation.
 16. The method of claim 10 wherein said step of separating said tubular member at an axial midpoint is pre-formed by a cutting operation.
 17. The method of claim 10 wherein metallic tubular is formed from wrapped sheep metal strip having a welded seam. 